NOMMU bogus syscall return values

[Rich Felker]

On Thu, Mar 03, 2016 at 04:01:21AM +0300, Dmitry V. Levin wrote:
> On Mon, Feb 29, 2016 at 05:59:44PM -0500, Mike Frysinger wrote:
> > On 29 Feb 2016 15:56, Rich Felker wrote:
> [...]
> > > The attached (very hackish at the moment) patch makes it work for me
> > > by eliminating the need to define NOMMU_SYSTEM to 1 and using clone()
> > > with CLONE_VM and a new stack for the child, instead of vfork. I see
> > > some potential issues that need to be addressed before this could be
> > > made into a proper solution, though:
> > > 
> > > 1. I'm not sure if all NOMMU systems strace supports have clone. If
> > >    so, I think vfork could be dropped completely and this used
> > >    instead.
> > 
> > uClibc has long required clone, so seems safe to assume it exists
> 
> strace assumes that PTRACE_SETOPTIONS works, which essentially means that
> linux kernel >= 2.6 is required.  On some architectures, newer kernel is
> required (e.g. >= 2.6.15 on mips for PTRACE_GETREGS support).  I don't
> know for sure whether all supported NOMMU systems have CLONE_VM, but
> I agree with Mike it seems safe to assume they do.

I was merely unaware whether strace supported any non-Linux systems.
Linux has had clone/CLONE_VM since basically forever (2.0, maybe
earlier) so if strace is Linux-only this is a non-issue. Should I try
to prepare a patch converting all the forks to clone so that NOMMU is
not a special case? What should be done about daemonized tracer mode?

Rich